Liquid crystal hot stamping foil

Abstract

The utility model relates to a liquid crystal hot stamping foil which sequentially comprises a base film layer, a stripping layer, a protective layer, a liquid crystal information layer and an adhesive layer which are stacked. The liquid crystal hot stamping foil provided by the utility model has the liquid crystal color changing effect of the existing liquid crystal self-adhesive label and the hot-pressing transfer characteristic of the hot stamping foil, can be applied to a flat-pressing flat or rotary-pressing rotary hot stamping machine, and can be completely transferred to a printing stock through a hot stamping process; therefore, the product with the liquid crystal light-variable effect and the anti-counterfeiting hidden information reading function is manufactured. The liquid crystal hot stamping foil is good in hot stamping effect, good in liquid crystal material transfer integrity, wide in application range and high in flexibility, adhesion and friction resistance can meet delivery requirements, other processing operation can be carried out after hot stamping, production efficiency can be improved and production cost can be reduced through the hot stamping process, and the liquid crystal hot stamping foil has application and popularization commercial value.

Description

Technical Field

[0001] The utility model belongs to the technical field of printing, and in particular relates to a liquid crystal hot stamping foil. Background Art

[0002] Liquid crystal materials, due to their molecular specificity, can produce visual effects of different colors from different angles through the directional arrangement of molecules. They are light-variable and can hide some information through the different orientation angles of liquid crystal molecules in different layers. This information can be read out under a liquid crystal reader of the same frequency. Therefore, liquid crystal materials are usually used as anti-counterfeiting or special decorations in the packaging field.

[0003] Since liquid crystal materials only have the property of cutting but not of being pressed, when the hot stamping process is used to transfer the liquid crystal material to the substrate, under the action of pressure, the molecules of the liquid crystal material will extend but not break, and the edge of the hot stamping plate will be deformed. However, due to the pulling force at the moment the hot stamping mold is opened, the liquid crystal material will usually be pulled apart, resulting in poor integrity of the hot stamping shape, residual liquid crystal material on the edge of the hot stamping plate, flashing, incompleteness, etc., and poor printing effect of the product (there will be flashing, incompleteness, etc. on the edge of the optically variable rectangular frame). Therefore, usually the liquid crystal material is cut into labels (such as liquid crystal self-adhesive labels), skylight film is applied, or the entire film is laminated and then cut into laminated paper for use. However, there are different problems in use. For example, labeling and skylight pasting both require dedicated labeling machines or window pasting machines, and the packaging boxes must be die-cut and cleared before operation. The process flexibility is poor, and the production speed of the labeling machine or window pasting machine is not fast. For example, the driving wheel of the labeling machine intermittently brings the label to the reel, and there is a pause time when the label is attached. Even the faster labeling machine has a speed of only 200 pieces / minute. Based on this calculation, it takes 50 minutes to produce 10,000 packaging boxes. The main problem with the entire sheet of lamination is that the cost of printed products is too high. Based on the company's commonly used 12-18 stitching and commonly used cutting size, it takes 555-833 sheets of paper to produce 10,000 packaging boxes, and the material cost reaches 23,000-25,000 yuan.

[0004] In order to solve the problems existing in the application of existing liquid crystal materials in packaging products, this application proposes an improved liquid crystal hot stamping foil based on the structural analysis and research of existing liquid crystal self-adhesive labels and ordinary hot stamping foils, so that it can be transferred to the substrate through hot stamping technology, giving full play to the advantages of hot stamping technology. Utility Model Content

[0005] In view of the above problems, the utility model provides a liquid crystal hot stamping foil.

[0006] The specific technical solution is: a liquid crystal hot stamping foil, which includes a laminated base film layer, a peeling layer, a protective layer, a liquid crystal information layer and an adhesive layer.

[0007] Furthermore, the base film layer is made of PET base film material.

[0008] Furthermore, the base film layer has a thickness of 35-50 μm.

[0009] Furthermore, the peeling layer has a thickness of 0.01-0.05 μm.

[0010] Furthermore, the organic silicon material content of the peeling layer is increased by 8%-15%.

[0011] Furthermore, the thickness of the protective layer is 15-20 μm.

[0012] Furthermore, the protective layer is formed by blending high-strength polytetrafluoroethylene and / or vinyl acetate with polyurethane.

[0013] Furthermore, the thickness of the liquid crystal information layer is 15-30 μm.

[0014] Furthermore, the liquid crystal information layer is composed of two layers of UV-dried oriented liquid crystal coating layers, and the orientation directions and colors of the two layers are different.

[0015] Furthermore, the thickness of the adhesive layer is 1.5 μm.

[0016] Furthermore, the adhesive layer comprises ingredients of polyurethane and polyvinyl acetal.

[0017] Furthermore, the polyvinyl acetal is polyvinyl butyral.

[0018] The utility model also provides a method for manufacturing the above-mentioned liquid crystal hot stamping foil, comprising the following steps:

[0019] (1) Coating a release agent on a 35-50 μm PET base film layer to form a peeling layer with a dry thickness of 0.01-0.05 μm;

[0020] (2) coating the release layer with a blend of high-strength polytetrafluoroethylene and / or vinyl acetate and polyurethane to form a protective layer with a dry thickness of 15-20 μm;

[0021] (3) coating a 15-30 μm liquid crystal information layer on the protective layer, first coating a first layer of liquid crystal on the protective layer, performing an orientation treatment after coating to form a first orientation direction, and then performing UV drying and curing; then coating a second layer of liquid crystal on the first layer of liquid crystal coating layer, performing an orientation treatment after coating to form a second orientation direction, and then performing UV drying and curing, the first orientation direction is opposite to the second orientation direction, forming a liquid crystal information layer with a light-variable effect or a liquid crystal information hiding effect;

[0022] (4) coating an adhesive layer containing polyurethane and polyvinyl acetal on the liquid crystal information layer, with a dry thickness of 1.5 μm;

[0023] (5) The liquid crystal hot stamping foil is pre-cut by a fine cutting method, and the pre-cutting direction is from the adhesive layer, the liquid crystal information layer, the protective layer, the peeling layer to the base film layer, and the pre-cutting depth is 35-40 μm.

[0024] The utility model also provides an application of the liquid crystal hot stamping foil. The liquid crystal hot stamping foil is applied to a hot stamping machine to produce products with liquid crystal light-changing effects and anti-counterfeiting identification hidden information.

[0025] Beneficial effects of the utility model: the liquid crystal hot stamping foil proposed by the utility model has both the liquid crystal color changing effect of the existing liquid crystal self-adhesive label and the hot pressing transfer property of the hot stamping foil, and can be applied to a flat-press flat or round-press round hot stamping machine, and is completely transferred to the substrate through the hot stamping process, thereby producing a product with liquid crystal light-changing effect and anti-counterfeiting reading hidden information. Moreover, the liquid crystal hot stamping foil has a good hot stamping effect, good liquid crystal material transfer integrity, and both adhesion and friction resistance can meet delivery requirements. After hot stamping, other processing operations can be performed, with a wide range of applications and high flexibility. The hot stamping process can also improve production efficiency and reduce production costs, and has commercial value for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a liquid crystal hot stamping foil in an embodiment;

[0027] Figure 2 is a flow chart for manufacturing the liquid crystal information layer in Example 2;

[0028] In the figure: 1-base film layer, 2-peeling layer, 3-protective layer, 4-liquid crystal information layer, 5-adhesive layer. DETAILED DESCRIPTION

[0029] In order to make the technical problems and technical solutions solved by the utility model more clearly understood, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model. Example 1

[0030] A liquid crystal hot stamping foil provided in this embodiment is proposed after structural analysis and research on existing liquid crystal self-adhesive labels and hot stamping foils. The liquid crystal hot stamping foil has both the liquid crystal color-changing effect of existing liquid crystal self-adhesive labels and the hot pressing transfer property of hot stamping foil, so that the liquid crystal material can be completely hot stamped onto the substrate, thereby overcoming the defects and shortcomings of existing liquid crystal material application methods such as labeling, skylight pasting, and lamination.

[0031] The liquid crystal hot stamping foil comprises a laminated base film layer 1, a peeling layer 2, a protective layer 3, a liquid crystal information layer 4 and an adhesive layer 5 in sequence, retaining the base film layer 1, the peeling layer 2 and the adhesive layer 5 similar to the existing hot stamping foil, adding the protective layer 3 and the liquid crystal information layer 4, and improving the specific structure and components of each layer, as follows:

[0032] The liquid crystal information layer 4 is different from the liquid crystal coating in the existing liquid crystal self-adhesive label. The liquid crystal coating in the existing liquid crystal self-adhesive label is thinner, with a thickness of about 5-10μm. It is superimposed with the oriented PET film layer to have the function of liquid crystal light-changing or anti-counterfeiting information reading. The liquid crystal information layer 4 of the present application must meet the hot stamping process, so the oriented PET film layer is cancelled. Therefore, it is necessary to perform orientation treatment immediately after the liquid crystal coating is applied to increase the light-changing effect and anti-counterfeiting hidden information reading. In addition, multiple layers of coating are required, and UV drying is required for each coating. Therefore, the thickness of the liquid crystal information layer 4 is increased to 15-30μm.

[0033] The liquid crystal information layer 4 is composed of two layers of UV-dried oriented liquid crystal coating layers, and the orientation directions and colors of the two layers are different. For example: the first layer has an orientation direction A, and the viewing angle a is reddish, and the viewing angle b is greenish; the second layer has text or pattern information, and the orientation direction B, and the viewing angle color is just opposite to the first layer (i.e.: the viewing angle a is greenish, and the viewing angle b is reddish). Of course, the color of the liquid crystal coating layer can be any color.

[0034] As the thickness of the liquid crystal information layer 4 increases, in order to prevent the liquid crystal hot stamping foil from deforming and curling, the thickness of the base film layer 1 is correspondingly increased from the general 12-16μm to 35-50μm. The thickening of the base film layer 1 will affect the hot stamping thermal conductivity, so a high thermal conductivity PET base film material is used.

[0035] In addition, since the liquid crystal material itself is relatively fragile, the liquid crystal coating of the existing liquid crystal self-adhesive label is protected by the surface material and the oriented PET film layer. However, when the liquid crystal information layer 4 of the present application is hot stamped, after the liquid crystal information layer 4 is peeled off from the peeling layer 2, the liquid crystal information layer 4 is exposed to the outside. Therefore, in order to protect the liquid crystal material, a protective layer 3 is added between the liquid crystal information layer 4 and the peeling layer 2. The protective layer 3 has a thickness of 15-20 μm and is made of a blend of high-strength polytetrafluoroethylene and (or) vinyl acetate and polyurethane. This film-forming structure can effectively improve the friction resistance of the protective film while ensuring transparency. The improved transparency can make the liquid crystal light-changing effect and the readability of liquid crystal hidden information better.

[0036] In this application, since the thickness of the liquid crystal information layer 4 and the protective layer 3 is much greater than the thickness of the dyeing layer and the aluminum plating layer of the existing hot stamping foil, the peeling thickness is significantly increased, and greater strength is required during peeling, so the content of the organic silicon material in the peeling layer 2 is increased by 8%-15%, and combined with the polytetrafluoroethylene in the protective layer 3, it is easier to peel and transfer during hot stamping. The thickness of the peeling layer 2 is 0.01-0.05μm.

[0037] The composition of the adhesive layer 5 is mainly based on the adhesive layer of the existing hot stamping foil. Considering the particularity of the liquid crystal material resin type, polyurethane and polyvinyl acetal are added to the original hot melt acrylic resin for multi-component copolymerization. Among them, polyurethane has the characteristics of oil resistance, friction resistance, aging resistance, high hardness and elasticity, and polyvinyl acetal has a low glass transition temperature, high viscosity and good film-forming properties. Adding these two components can improve the overall performance of the adhesive layer 5. The polyvinyl acetal can preferably be polyvinyl butyral, and the thickness of the adhesive layer 5 is 1.5μm.

[0038] In summary, the thickness of the base film layer 1, the peeling layer 2, the protective layer 3, the liquid crystal information layer 4 and the adhesive layer 5, the thickness of the entire liquid crystal hot stamping foil is about 2-3 times that of the existing hot stamping foil. Example 2

[0039] This embodiment provides a method for manufacturing the liquid crystal hot stamping foil described in Embodiment 1, comprising the following steps:

[0040] (1) Coating a release agent on a 35-50 μm PET base film layer to form a peeling layer with a dry thickness of 0.01-0.05 μm;

[0041] (2) coating the release layer with a blend of high-strength polytetrafluoroethylene and (or) vinyl acetate and polyurethane to form a protective layer with a dry thickness of 15-20 μm;

[0042] (3) coating a 15-30 μm liquid crystal information layer on the protective layer, first coating a first layer of liquid crystal on the protective layer, performing an orientation treatment after coating to form a first orientation direction, and then performing UV drying and curing; then coating a second layer of liquid crystal on the first layer of liquid crystal coating layer, performing an orientation treatment after coating to form a second orientation direction, and then performing UV drying and curing, the first orientation direction is opposite to the second orientation direction, forming a liquid crystal information layer with a light-variable effect or a liquid crystal information hiding effect;

[0043] The production process of the liquid crystal information layer is as follows Figure 2As shown, a first layer of liquid crystal coating is performed on the PET film on which a protective layer has been completed. After coating, the film passes through polarized light A of a light orientation device 1 to form an orientation direction A, and then is cured by a UV mercury lamp with a main wave of 365nm (a more commonly used main wave) and a curing power of 80W / cm (a more commonly used UV curing power of 80-120). Then, a second layer of liquid crystal coating is performed. After coating, the film passes through polarized light B of a light orientation device 2 to form an orientation direction B, and then is UV cured with a curing power of 100W / cm. In this way, two layers of liquid crystal coating layers with opposite orientation directions are obtained, which have a light-variable effect or a liquid crystal information hiding effect when observed from different angles.

[0044] The polarized light can be adjusted in polarization angle and direction through a filter to obtain different polarized light, such as polarization A, polarization B, polarization C, polarization D, etc., so that the liquid crystal coating layer is oriented in directions A, B, C, and D to form color-changing effects at different angles.

[0045] (4) coating an adhesive layer containing polyurethane and polyvinyl acetal on the liquid crystal information layer, with a dry thickness of 1.5 μm;

[0046] (5) The above-mentioned liquid crystal hot stamping foil is pre-cut by fine cutting method, and the pre-cutting direction is from adhesive layer, liquid crystal information layer, protective layer, peeling layer to base film layer, and the pre-cutting depth is 35-40μm. Since the thickest liquid crystal information layer 4 is 30μm, the pre-cutting is based on the principle of cutting through the liquid crystal information layer 4, and the hot-melt protective layer 3 is easily peeled off from the peeling layer 2 during hot pressing. Whether the protective layer 3 is cut through does not affect the hot stamping transfer, so the pre-cutting depth is sufficient to ensure that the edges of the liquid crystal material are neat during hot stamping. At the same time, when the liquid crystal information layer 4 and the protective layer are both the thinnest 15μm, together with the peeling layer 2 and the adhesive layer 5, only about 3μm of the base film layer 1 will be cut. Since the base film layer 1 is thick, the liquid crystal hot stamping foil will not be pulled apart during high-speed operation.

[0047] The production of this liquid crystal hot stamping foil fully combines the hot pressing transfer principle of the hot stamping process and the characteristics of the liquid crystal material itself. The dyeing layer and the aluminum plating layer of the existing hot stamping foil are replaced with the liquid crystal information layer. At the same time, in order to adapt to the liquid crystal information layer, the base film layer, the peeling layer and the adhesive layer of the existing hot stamping foil are adjusted accordingly, so that the produced liquid crystal hot stamping foil is suitable for the hot stamping process. The fine cutting method is also used to pre-cut the liquid crystal hot stamping foil. The fine cutting method (such as laser cutting) has high precision and can accurately control the cutting thickness. It can cut through each coating without cutting through the PET base film layer, ensuring that the liquid crystal material can be completely transferred during hot pressing transfer, avoiding edge incompleteness, burrs, jagged edges and the like during transfer. Example 3

[0048] This embodiment provides an application of the above-mentioned liquid crystal hot stamping foil described in Example 1. The liquid crystal hot stamping foil can be used on a hot stamping machine, and both flat-pressing and round-pressing hot stamping are possible. The liquid crystal material is transferred to the substrate by hot pressing through the hot stamping machine to produce a product with liquid crystal light-changing effect and anti-counterfeiting hidden information.

[0049] When hot stamping liquid crystal foil, since the liquid crystal hot stamping material is thicker than the existing hot stamping foil, its thermal conductivity is relatively poor, and the temperature adaptation range of the film layer of the liquid crystal material is narrower than that of the existing hot stamping foil. During the hot stamping process, the temperature and holding time need to be more precisely controlled. The holding time needs to be slightly longer than the existing hot stamping foil. The holding time is sufficient to allow the liquid crystal information layer to be smoothly peeled off to the surface of the substrate, but the temperature cannot be high. If the hot stamping temperature is high, the film layer of the liquid crystal material is prone to wrinkling. If the foil is not smooth during the hot stamping process, it is easy to cause waste. This is also different from the existing hot stamping foil. The existing hot stamping foil is easier to stamp when the temperature is slightly higher.

[0050] After many tests, the best setting temperature for hot stamping of liquid crystal hot stamping foil is 120℃-135℃ (the temperature of existing hot stamping foil is generally set at above 140℃), and the holding time is preferably 0.5-1.5s (the holding time of existing hot stamping foil is shorter, generally less than 0.5s). The machine speed can reach 2000-4500 sheets / h. When the machine speed is 2000 sheets / h, the holding time is about 1.5s, and when the machine speed is 4500 sheets / h, the holding time is about 0.5 seconds.

[0051] The edges of the packaging products printed with this liquid crystal hot stamping foil are smooth and perfectly integrated with the surrounding printed coating. When the area is illuminated by a mobile phone screen, the hidden pattern in the area can be observed, and the pattern can be used as an anti-counterfeiting mark.

[0052] After hot stamping, the liquid crystal hot stamping foil can also be processed in other ways, such as re-printing color ink, or glazing oil, matt oil, snowflake and other synergistic inks, which will not affect the liquid crystal light-changing and anti-counterfeiting effects, and the application is more flexible.

[0053] When the company uses the liquid crystal hot stamping foil in the hot stamping machine to make packaging products, it takes only 30 minutes to produce 10,000 packages (555 sheets) at the slowest flat-bed machine speed of 1900 sheets / h, 18 plates per sheet, and the production cost of the hot stamping label is about 0.04-0.13 yuan / piece according to the size of the dosage box. It only takes 400-1300 yuan to produce 10,000 packages. In addition, it has a good hot stamping effect on the surface of white cardboard, water-based coated paper, water-based varnish, hot stamping varnish, and matt oil printing materials, and the adhesion and friction resistance can meet the delivery requirements. The speed and hot stamping effect of the round hot stamping machine are better than those of the flat-bed hot stamping machine. The larger the production volume, the higher the efficiency of the application in this way.

[0054] In addition, the liquid crystal hot stamping foil is transferred by hot stamping. After hot stamping, the base film layer on the surface of the liquid crystal material has been peeled off and can be recycled like ordinary hot stamping film, which is more environmentally friendly.

[0055] In summary, the liquid crystal hot stamping foil is applied to the hot stamping machine, has good hot stamping effect, high production efficiency, low production cost, and has commercial value for promotion and application.

[0056] The present invention is described in detail above through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the embodiments described above, and any modifications, equivalent substitutions, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid crystal hot stamping foil, characterized in that: It comprises a base film layer (1), a peeling layer (2), a protective layer (3), a liquid crystal information layer (4) and an adhesive layer (5) which are stacked in sequence; The liquid crystal information layer (4) is composed of two layers of UV-dried oriented liquid crystal coating layers, and the orientation directions and colors of the two layers are different.

2. The liquid crystal hot stamping foil according to claim 1, characterized in that: The base film layer (1) is made of PET base film material and has a thickness of 35-50 μm.

3. The liquid crystal hot stamping foil according to claim 1, characterized in that: The organic silicon material content of the peeling layer (2) is increased by 8%-15%.

4. The liquid crystal hot stamping foil according to claim 1, characterized in that: The protective layer (3) has a thickness of 15-20 μm.

5. The liquid crystal hot stamping foil according to claim 4, characterized in that: The protective layer (3) is formed by blending high-strength polytetrafluoroethylene and / or vinyl acetate with polyurethane.

6. The liquid crystal hot stamping foil according to claim 1, characterized in that: The liquid crystal information layer (4) has a thickness of 15-30 μm.

7. The liquid crystal hot stamping foil according to claim 1, characterized in that: The ingredients of the adhesive layer (5) include polyurethane and polyvinyl acetal.

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